1 /*-
2 * perm.c - check user permission for at(1)
3 *
4 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
5 *
6 * Copyright (C) 1994 Thomas Koenig
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. The name of the author(s) may not be used to endorse or promote
14 * products derived from this software without specific prior written
15 * permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31
32 /* System Headers */
33
34 #include <sys/types.h>
35 #include <err.h>
36 #include <errno.h>
37 #include <pwd.h>
38 #include <stddef.h>
39 #include <stdio.h>
40 #include <stdlib.h>
41 #include <string.h>
42 #include <unistd.h>
43
44 /* Local headers */
45
46 #include "at.h"
47 #include "perm.h"
48 #include "privs.h"
49
50 /* Macros */
51
52 #define MAXUSERID 10
53
54 /* Structures and unions */
55
56 /* Function declarations */
57
58 static int check_for_user(FILE *fp,const char *name);
59
60 /* Local functions */
61
check_for_user(FILE * fp,const char * name)62 static int check_for_user(FILE *fp,const char *name)
63 {
64 char *buffer;
65 size_t len;
66 int found = 0;
67
68 len = strlen(name);
69 if ((buffer = malloc(len+2)) == NULL)
70 errx(EXIT_FAILURE, "virtual memory exhausted");
71
72 while(fgets(buffer, len+2, fp) != NULL)
73 {
74 if ((strncmp(name, buffer, len) == 0) &&
75 (buffer[len] == '\n'))
76 {
77 found = 1;
78 break;
79 }
80 }
81 fclose(fp);
82 free(buffer);
83 return found;
84 }
85 /* Global functions */
check_permission(void)86 int check_permission(void)
87 {
88 FILE *fp;
89 uid_t uid = geteuid();
90 struct passwd *pentry;
91
92 if (uid==0)
93 return 1;
94
95 if ((pentry = getpwuid(uid)) == NULL)
96 err(EXIT_FAILURE, "cannot access user database");
97
98 PRIV_START
99
100 fp=fopen(PERM_PATH "at.allow","r");
101
102 PRIV_END
103
104 if (fp != NULL)
105 {
106 return check_for_user(fp, pentry->pw_name);
107 }
108 else if (errno == ENOENT)
109 {
110
111 PRIV_START
112
113 fp=fopen(PERM_PATH "at.deny", "r");
114
115 PRIV_END
116
117 if (fp != NULL)
118 {
119 return !check_for_user(fp, pentry->pw_name);
120 }
121 else if (errno != ENOENT)
122 warn("at.deny");
123 }
124 else
125 warn("at.allow");
126 return 0;
127 }
128